Cell Culture: mycoplasma suspected

1. Ranked causes

   1. Mycoplasma contamination of the working cultureSlow growth / odd metabolism without turbidity; lastMycoplasmaTestAt missing or overdue on the Lab Index item.
   2. Serum or reagent lot carrying mycoplasmaNew bottle coincides with onset across independent flasks.
   3. False-positive risk from assay inhibition / kit lot — confirm with orthogonal testPCR+ but luminescence− (or vice versa) on the same extract.
   4. Shared media bottle or incubator shelf spreading mycoplasma between linesMultiple lines in the same incubator underperform after one positive flask.

2. Recovery steps

   1. Test for mycoplasma (PCR and/or luminescence) on the suspect line immediatelyConfirms or clears the leading material cause before discarding stock.
   2. Quarantine positives; discard or treat only under lab policy — never share media bottlesStops horizontal spread while decisions are made.
   3. Retest all active lines sharing the incubator; update lastMycoplasmaTestAt on Lab IndexKeeps Lab Index dates current so Diagnostics can raise this cause next time.
   4. Thaw a mycoplasma-negative authenticated vial and restartClean restart beats chronic underperformance from a silently contaminated stock.

3. Controls first

   • Did a mycoplasma-negative control extract / kit blank stay negative?If no: Kit or assay issue — re-run with a fresh kit lot before discarding cultures.
   • Is media visibly turbid?If no: Consistent with mycoplasma — run PCR/luminescence rather than visual-only checks.

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